The present invention relates to a power-assisted steering device for a vehicle, comprising control means acting on steering means, the control means comprising a rotatable transmission element having an input shaft and an output shaft which are coaxial and are located one after the other and are coupled elastically by a torsion bar, a limited relative angular play being provided between said shafts to permit an angular offset under the action of the control means and against an elastic restoring action of the torsion bar, power-assistance means which, in response to such an angular offset, are allowed to act on the turning means in the same direction as the control means, said power-assistance means comprising a hydraulic unit, an actuator acting on the turning means and a distributor located between the unit and the actuator and having a fixed housing and at least one rotor rotating integrally with one of said shafts, a sealing gasket between each of said shafts and the housing of the distributor, and a stop means in axial direction between the input shaft and the housing so as to prevent the input shaft from separating from the output shaft, if the torsion bar breaks.
This stop means has an important function for safety. In fact, the torsion bar, which elastically couples the input shaft and the output shaft, positions these two shafts axially relative to one another. If, for any reason, the torsion bar breaks, it no longer retains the input shaft axially relative to the output shaft.
In general terms, the rotating transmission element consisting of a steering column has a telescopic assembly. If, therefore, the input shaft were to separate from the output shaft, not only would the power assistance no longer operate, but, and this is serious, the driver could no longer even take advantage of a take-over of the turning torque by means of a manual stand-by facility.
Consequently, the stop means in an axial direction is provided to prevent such a separation of the input shaft.
In general, this stop means consists of a circlip or any other projection formed, for example, by the end of a pin, mounted on the input shaft actually within the distributor and interacting as a stop, if the torsion bar breaks, with the housing or a member integral with the housing axially. However useful this arrangement may be for safety, it nevertheless has the disadvantage of complicating the construction.
The subject of the present invention is a power-assisted steering device for a vehicle, of the type mentioned above, the construction of which is especially simple.